The decrease in the world's supply of petroleum and the increasing need for energy to supply the constantly growing world population requires an increased production of this raw material by means of improving the technology of producing crude oil. As is well known, hydrocarbon sources include in addition to petroleum obtained from underground deposits, also crude oil which is contained and extracted from tar sands in surface and underground deposits, for example in Canada and Venezuela.
Such tar sands contain sand and clay as the major components in admixture with high viscosity crude oils and bitumen. These tar sands are dredged deposits attainable from the surface after removal of rubble and treated with hot water in large separation tanks. A foaming up of the crude oil occurs thereby, while the solid materials contained in the mixture settle on the bottom of the tank by means of gravity separation. The crude oil removed from the separation tank is separated by distillation into light and heavy fractions. The light fraction must for the most part be enriched by hydrogenation with hydrogen in order to obtain from this crude oil fraction a product which is similar to petroleum obtained in liquid form from oil wells.
Employing this procedure, separation of the crude oil and especially of the bituminous component from the clay is incomplete, so that the solid portion separated from the foamed crude oil is a clay-oil-bitumen slime, which hitherto has been stored in basins. In order to improve the separation during treatment of the tar sands with hot water at a temperature of 80.degree. C., alkalis can be added to the water. The hydrophobic reactions between the components of the bitumen and the clay are reduced thereby. The alkalis form surface active salts with the acids contained in the bitumen and these facilitate the separation of the bitumen from the solid materials of the tar sand. Of course, compounds of this type seem to contribute to the formation of reactive clay slimes. Therefore organic solvents, such as gasoline or kerosene, have also been added during hot water treatment of the tar sands, in order to decrease the viscosity of the bitumen. Finally, it has been recommended that surface active substances, such as soap or non-ionic detergents be added together with the alkalis or alone to the hot water.
In order to open up the tar sand deposits which are not accessible above ground, it is known from "Oil Sands" (1977), pages 584 to 592, to inject steam into the deposits until the highly viscous crude oil of low mobility is converted by heating into a crude oil of low viscosity and good fluidity. To this end, hot water is injected into the deposits through injection bore holes at a temperature of 150.degree. to 260.degree. C. or steam is employed at temperatures of up to 315.degree. C.
The extraction of crude oil by the heating of tar sand deposits can be carried out by the so-called cyclic steam stimulation method whereby steam is injected into tar sand deposits through a bore hole for a certain period of time, such as a month. Then the crude oil mixture is drawn out of the same bore hole until the tar sand deposit in the vicinity of the bore hole cools down so much that the crude oil no longer flows. This procedure can be repeated alternately until no more crude oil can be obtained from the tar sand deposit.
According to another known process, the drawing out of the crude oil heated by steam from underground tar sand deposits can be carried out through the discharge bore holes which have been made lower in tar sand deposits in addition to injection bore holes. Here it has proved useful to have underground fissure connections between the injection bore hole and the one or more extraction bore holes produced by means of hydraulic shock or the introduction of steam under a pressure so high that this leads to the formation of fissures. In the latter case, a solution of caustic soda and surface active agents can additionally be injected into the tar sand deposits with the steam, in order to emulsify the crude oil in the steam condensate, as well as make it more capable of flowing. The removal of oil from the deposits according to this process, however, is still unsatisfactory.
In the publication of the Canadian Institute of Mining and Metallurgy (CIM) in "CIM Special Vol." 17 (1977), at pages 705 to 710, a scientific investigation of bitumen extraction from so-called tar sands with the aid of microbiological surface active agents is reported. As a result of these investigations, it was determined that surface active agents produced by a micro-organism of the Corynebacterium type are very effective in the separation of bitumen from sand and clay; in the flotation of the separated bitumen; as well as for the purification of the remaining sand as a residue. The concentration of the bitumen in the clumps of bitumen and sand contained in the residue is viewed as a measure of the effectiveness. The higher the concentration of the bitumen in these clumps, the more sand is washed out in purer form. If, by hot water treatment without the addition of detergents, the concentration of the bitumen amounts to 12 wt. %, it rises to 30.7 wt. % with the addition of 0.01 wt. % of a culture liquor of Corynebacterium in kerosene, while other synthetic surface active agents in a concentration of 0.02 wt. % only effect an increase of the bitumen concentration to 28.3 wt. %. Of the surface active agent contained in the culture liquor of the Corynebacterium, it is only known that it is a lipid. The unpurified surface active substance decreases the surface tension of water from 72.05 dyne/cm to only 51.4 dyne/cm in a concentration of 150 mg/l.
The German laid-open publication DE-OS 28 05 823 discloses a process for obtaining petroleum by flooding petroleum deposits with dispersions of non-ionic, surface active agents in water. According to this process, glycolipids of a certain structure are produced in the first step by hydrocarbon consuming microorganisms under aerobic conditions. These are separated in a second step from the cell mass by a temperature-, pH-, or osmotic shock, and the aqueous phase with the glycolipids dispersed therein is used directly as the flooding agent or added to the flood water or separated by extraction from the cell mass and added to the flood water.
From the foregoing, it is seen that a need exists for a truly effective process for the extraction of crude oil from tar sands employing steam or hot water.